Monday, July 16, 2012

Silver studded blues threatened by bad weather

There’s only one colony of silver studded blues in Snowdonia and that’s at Hafod Garegog National Nature Reserve, between Porthmadog and Beddgelert. It’s one of only six sites in Wales and the only site in the UK on wet peatland, but this summer of wet weather could wipe it out.

They need the help of black ants. The females lay their eggs singly on stalks of heather where they detect suitable ant pheromones. Next spring the resultant larvae are either picked up by the ants or crawl into the nearest ants’ nest, where they enjoy a warm and humid environment, safely protected from predators, with the ants collecting protection money in the form of a sugary secretion. Larvae crawl out of the nest to feed on tender shoots of heather before pupating, sprouting blue wings (or brown if they are females) and flying off to mate.

At Hafod Garegog they can usually be seen in July and the first half of August with individuals living for just a few days. Without warmth and sunshine they won’t mate and that would be a disaster from which they can’t recover. These butterflies are weak fliers so there is no chance of new blood flying in from another colony, such as the Great Orme.

On Sunday 15th July there was a rare moment of good weather and we were fortunate to see them flying (see film below). But David Wilkinson fears their numbers are significantly down.